Need More Examples of Mechanical Parts

General Discussion
1

Dear Form Labs -

I see a lot of figures/characters being shared here on the forums and on your blog.  These are very cool and show the power of the Form 1.  However, I have not seen many mechanical parts featured at all.  I’m guessing your demographic includes a fair amount of design professionals who have to design parts that fit together and function as an assembly (as in many consumer product applications).  It would be wonderful to see more of this type of work showcased on your blog.  I say this because I have not had great luck so far with my Form1’s accuracy - parts that should mate together do not align so well…edges that should be straight are not…faces that should be flat are not, etc, etc.    I’m wondering if the Form1 is not a good tool for product design, but is intended more for creative artists that need to produce character art and the like where dimensional accuracy and tolerances are not so critical.  I’d love to hear others’ opinions about this subject, as well.

2

I hate saying this but, the Form 1 does seem to have issues with accuracy which tends to make printing mechanical parts somewhat hit and miss.  I REALLY wish mine would produce accurate parts reliably.  I have gone through two liters of resin now and I would say only half of my parts come out accurate enough to call good.  Its a shame really.  I will probably have to sell mine as the accuracy prevents simple objects (like large gears) from working and the cost of resin prevents me wanting to print 5 times just to get a decently accurate part.

3

To build small and accurate mechanical parts is exactly the purpose we’ve odered Form1 and why we are waiting since almost 9month for it. We expect to cover the range between small, precise and large, robust parts by having the Form1 running beside our FDM Printer (HP Designjet 3D). Your experiece doesn’t make us really confident to get met our expectations on Form1. Is the printing quality (accuracy) affected by the part orientation? Could you please post some pics to show the issues? Thanks in advance

4

One reason we feature a lot of character and modeling work, is that those users often publicly share and promote their models. The majority of our engineering users are typically working on projects that they are not at liberty to disclose. I will say that we have a number of Form 1s at work in the largest engineering and product companies in the country – and they’ve been using them to great success.

In the office, we use our own Form 1s to prototype and test improvements, make custom analysis rigs, and print many other demanding components.

Hovey, if you’re seeing inaccuracies of a magnitude large enough to impair basic functionality, your printer may have a hardware issue (that will likely grow worse). Please open up a ticket with support if you haven’t already. You can shoot a note to support@formlabs.com.

We’re also constantly improving the accuracy of the Form 1 through a variety of software tweaks and fixes. Marco – I’m confident that you’ll find that the Form 1 can handle what you throw at it – and if it doesn’t, we’ll work with you to make it right.

5

This is very encouraging to hear, Sam.  Thank you for chiming in.  While I have not had great success with printing dimensionally accurate mechanical components to date, I will say that the Form Labs support has been easy to work with, and eager to help make things right.  I had some major problems with my machine and just sent it back - should be receiving a replacement soon.  I will update this thread based on my new findings once the replacement arrives.

6

First I didn’t mean my post to be a bashing of Form Labs or their current products.  I think they make one of the best desktop 3D printers on the market right now.  And as a disclaimer I have had issues and am on my second Form1 printer.  I do want to say that their customer service has been first rate!  Did I mention that their customer service has been great?  Because it has.

Yes I agree that confidentiality will severely reduce the number of people able to post what they make.  But like basically all printers marketed to the consumer, the accuracy of the part still tends to be poor.   The resolution is VERY good which makes for smooth surfaces, but that is not the same as accuracy. The precision, is also very good, but that too is not the same as accuracy.  Accuracy is how close to the design dimensions the part ends up at.  So a 1" cube should end up printed at exactly 1" if the machine is perfectly accurate.  I have used FDM printers that do better than the Form1 in this area, however their surface quality is no where near as good.  There is no perfect machine!

Looking at the Tech specs listed (http://formlabs.com/pages/tech-specs) Form labs conveniently fails to mention the accuracy/tolerance of the machine.  Based on conversation with others ~1.5% seems to be standard but I would love to hear from Form Labs with an actual number.  At any rate this is within most peoples ability to visually say, “Yes that looks right.”  however when building gears or other tight tolerance parts 1.5% is not very good at all.  Consider a machinist who only worked to such loose tolerances, for a 2" dia gear that comes out to +/- 0.03"!  That is considered pretty good for consumer printers, but still bad by machinist standards.  Very bad. Even worse if your error on two parts is additive rather than cancelling in nature this can double.  Not that I have ever been able to print a truly round shaft, but a 0.5" shaft would still be out by almost 8 thousandths, not exactly round.  Based on my experience, I would place positional accuracy no better than 0.4mm when working, but yes I have had two bum units.  To further complicate the issue, alcohol and curing can cause some distortion as well.  So don’t leave your parts in alcohol or in your curing cabinet for too long.

Yes I could easy print all sorts of demanding objects, but I haven’t seen many people print dimensionally demanding parts with their form one.  This is a weakness generally shared by all consumer printers and many industrial printers.  As a challenge print a couple of 0.75" dia gears with a 24 tooth pitch.  See how they well mesh when mounted on fixed shafts.  Or better yet, print a piston and sleeve.  Its not so easy!  I am sure some of you will succeed in making those, but most probably wont on their first or second try.

I think there are several issues that cause this. The peel process can cause the part to move, fall off etc. as the force involved is surprising large.  Perhaps some teflon could be introduced here?  Also the laser path does not stay linear as it goes from center, the beam expands slightly and the angle of incidence as the laser beam passes thought the differing materials in the tray causes a non-linear change in angle.  Analog PID controls which are much harder to properly set, probably don’t help either.  All of that would require a cost increase to fix, so I don’t expect Form Labs to change it.

So yes I do like my printer, but unless my next one works incredibly better than my last two I don’t think I will be considering accuracy the strong point of the Form 1.  High resolution, and high accuracy is the holy grail of 3D printing. The Form 1 is a great printer, its just not a perfect printer.

7

With PreForm 1.2.1 and the ‘fine tune’ ability, I’m getting under 1% overall accuracy now.  I’m working on electronics assemblies to go inside plastic injection molded cases (using the Form1 to protoype the plastic portion) and in general I’m pretty happy with the Form1 at the early Kickstarter price.  It’s not all I was hoping it would be, but it’s still quite useful.  I find that I’m using it essentially as a ‘preview’ printer-- I can get a print that’s 80-90% as good as a service bureau delivered ‘same day’ for a few bucks. For me, the main advantage is time.

The main disadvantage that I see is the support structure and the resulting ‘tits’ (for lack of a better word) left by it.  Without a lot of cleanup you’re really looking at something in a typical box-like enclosure that’s going to have five good faces and one really messed up one.  I’ve taken to printing parts twice-- once for an accurate interior model free of distortion and once for a nice exterior finish.  The main problem being things like thing walls (say a 1mm wall with a thinner 0.5mm section on top of it) where PreForm insists on placing supports next to the thin section-- the resulting bumps easily fuse with the thin wall section and are a real PITA to remove.

On the other hand, once you have the printer it can indeed change how you work-- it becomes very easy to “just try it” and print something immediately.  The week+ wait (I typically use Shapeways to keep costs down) to try a part goes away, so you can get things dialed in printing from the Form1, then just order a single ‘proof’ quality print from a service bureau to check everything at the end.  Looking around my desk I see parts that would have cost at least $500+ at Shapeways (and taken months of design iterations) that I’ve done with part of a bottle of grey and couple weeks of time.

It also doesn’t hurt that I remember our first SLA models in the late 1990’s which were comparable to the Form1’s output, but at 100x the cost per part, so from a “now I have my own” standpoint that’s pretty cool, so I cut them more slack for that fact.

8

Whoops-- wrong first image there.  And of course I can’t delete it-- I hate this forum software. :wink:

9

This is 50/50 B9 Cherry Red and Grey resin mix-- it’s much more flexible that straight-up Form Grey. (That leads to some dimensional issues s you’ll see it can ‘bow’ in these pictures with thin wall sections, but it’s a lot easier to photograph than the Grey.)  Note the “good side” where a circuit board sits in the bosses easily holds ~15/1000th’s when I measure it which is probably better than the edge router tolerance when making the circuit boards, but the same part on the ‘exterior’ side is just a mess from the support structure touch points…  (The ‘dots’ are in the 0.4mm x 0.3mm range give or take, so when they’re on a 1mm thick section that’s a lot.  I need to go back to ‘Clear’ again and see how that works.)

The wall thickness on this is 1mm and the thin lip around the top edge is only 0.5mm-- tolerances are close enough at this point (after using “Fine Tuning” to tweak it) that I can mate my Form1 printed parts to Shapeways sintered Nylon parts without issue.

10

Clay, you may try to print cover like this without supports. Just position it upside down like on the upper photo.

11

I printed some mechanical parts for a prototype and had the same results in lack of accuracy than others:

tube, 20mm diameter, wall thickness 1mm. Measured an error of 0.2mm (2 tenth of a millimetre!) in roundness. In this tube another part must fit, wihich is designed 0.2mm smaller in diameter than the inner diameter of the tube. But it does not fit.

Try and error, printed some “reference” parts to find a possible scale factor for the finetuning feature (rectangular tube, 15mm x 15mm x 15mm, inner 10mm x 10mm). Outer measurements with no problems, +/- 0.01mm. Height completely out of accuracy, + 0.5mm. Inner measurements in X and Y axis -0.2mm.

Formlabs support is in touch. They always answer to my mails and I hope they find a solution for this problem or switch the printer. This lack of accuracy stopped my work on this prototype. And the problem is the inconsistance of the imprecision…

Hope there are some solutions…

1 Like
12

If you are having issues, we will find a solution for you asap.

However, if you are looking for examples or mechanical parts, you can checkout the new Applications section on our website here:

http://formlabs.com/applications/engineering/

15

I run a machine shop and design group.
I’ll sell you our Formlabs 1+ complete with 5 bottles of resin, a spare build platform, 3 or 4 unopened resin trays. Our 1+ has only 10-20hrs of operation. It’s yours for $3000 OBO.

-John Buckley
The John B. Pierce Lab
290 Congress Avenue
New Haven, CT 06519
(203) 562-9901 ext.223
email: jgb@jbpierce.org

16

John I would put your offer in the for sale section. You might struggle to get that price. With the launch of the form 2 they are generally going for half that price.